query about RbhugItA and zivarahasya

[Alberto Pelissero]

Dear colleagues,
a student of mine would like to know if there is some relationship between
the RbhugItA and the zivarahasya, and more particularly:
is the zivarahasya derived (or pretended to be derived) from some purANa?
is the zivarahasya more akin to zaivasiddhAnta or to trika?
is the RbhugItA contained (or pretended to be contained) into the
zivarahasya?
is the RbhugItA ascribed to someone or not?
Thank You in advance,
Alberto Pelissero
Dept. of Oriental studies
University of Torino